TP53 and head and neck squamous cell carcinoma: However, a study in HNSCC cell lines suggested that p53 status is an important determinant in the mechanism of cell death triggered by MK-1775, whereby p53-containing cell lines (UMSCC-47) result in mitotic catastrophe, whereas, p53-mutant cells (SCC-15, SCC-25 and Cal-27) increase apoptosis following combination treatment [115].